Hydraulic cutters



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iorneyl United States Patent O 3,407,693 HYDRAULIC CUTTERS Daniel Greer McNair, 583 Govan Road, Glasgow, SW. 1, Scotland Filed July 5, 1966, Ser. No. 562,793 4 Claims. ('Cl. 83-635) ABSTRACT F THE DISCLOSURE An hydraulic cutter has an hydraulically operable piston-and-cylinder device including a manually operable hydraulic pump, and a cylindrical fluid reservoir for the supply of fluid to the pump at the opposite side thereof from the cylinder of the device and coaxial with the cylinder. A spring-urged plunger is housed in the reservoir to maintain a proper fluid supply to the pump irrespective of the orientation of the cutter. A U-support for the workpiece is provided on the cylinder and a cutting blade mounted on the piston of the device is movable on operation of the pump to penetrate the workpiece.

This invention relates to hydraulic cutters.

The object of the invention is to provide a compact, easily operated hydraulic cutter suitable for cutting metal work pieces such, for example, as bars, chain links and joists.

According to the present invention an hydraulic cutter comprises an hydraulic piston-and-cylinder actuating device; a U-support for the workpiece at one end of the cylinder of the actuating device; a cutting blade mounted on the piston of the actuating device and movable inwards from one limb of the U-Support to penetrate the workpiece; a manually operable hydraulic pump at the other end of the cylinder of the actuating device and in fluid communication therewith; a cylindrical fluid reservoir in fluid communication with the pump and at the opposite side of the pump from and coaxial with the cylinder of the actuating device; and a spring-urged plunger in the reservoir for maintaining a nid supply to the pump irrespective of the orientation of the reservoir.

An embdiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side elevation of an hydraulic cutter according to the present invention, and

FIG. 2 is a top plan view of the hydraulic cutter shown in FIG. l.

Referring to the drawings:

An hydraulic cutter has a cylinder 1 with a close-fitting piston 2 therein. A long cylindrical ram 3 concentric with the piston 2 has one end screwed into the piston. The ram 3 is rigidly secured to the piston 2 by welding the mating threads at the ram end, as shown in FIG. 1. A knife blade 4 having a cutting edge 4a is fitted into a slot 5 at the other end of the ram 3 and is secured in the slot by a pin 6. The ram 3 is of such length that the blade 4 projects from the cylinder when the piston 2 is in its innermost position as shown. A leather-cup seal 7 is clamped to the piston 2 by means of a disc 8 and a set pin 9 screwed into the ram 3.

On the outer end of the cylinder 1 is a U-shaped jaw block 10 which includes a jaw 14 spaced from said outer end and a jaw screwed to said outer end. A return spring 11 is positioned between the jaw 15 and the piston 2 to tend to keep the piston normally in its inner-most position. A knife blade 13 having a cutting edge 13a is secured to a cylindrical blade holder or plug 12 which in turn is screwed into the jaw 14 of the jaw block 10 by means of the hexagonal formation 16 thereon. The ram 3 is slidable through an aperture 15A in the jaw 15 of the 3,407,693 Patented Get. 29, 1968 jaw block 10, the blades 4 and 13 being co-planar and the two cutting edges 4a, 13a opposing each other. The ram 3 and consequently the blade 4, are kept from turning by a key 17 on the ram 3 slidable in a keyway 18 in the jaw 15. In adjusting the plug 12 it is turned until the cutting edge 13a is aligned with the cutting edge 4a, and it is then locked in this adjusted position =by a collar 19 which mates with the hexagonal formation 16 and is secured to the jaw 14 by pins 20. The work piece engages the base 21 interconnecting the jaws 14 and 15.

A block 22 embodying an hydraulic pump is welded to the end of the cylinder 1 remote from the jaw block 10. The disc 8 of the piston 2 is urged against a face 23 of the block 22 by the spring 11. Welded to the pump block 22 at the opposite side thereof from the cylinder 1 is a reservoir cylinder 24 co-axial with the cylinder 1 and containing pressure fluid 25.l The hydraulic pump includes a bore 26 having a plunger 27 therein. The plunger 27 is attached to a handle 28 through a pin and slot mechanism 29, the handle being pivoted about a pin 30. A passage 31 having a nonreturn valve 32 therein leads from the reservoir 24 to the bore 26 of the hydraulic pump. Another passage 34 `having therein a nonreturn valve at 33 leads from the bore 26 to a recess 35 formed inthe block 22 and opening into the cylinder 1. A third passage 36 leads directly from the recess 35 to the reservoir 24, this passage 36 having therein a shut-olf ball valve 37 actuable by the screw pin 38.

The cylinder 24 is closed at its free end by a screwed-on end plate 39, `and has therein a piston 40. A rod on the piston 40 has two threaded end portions 46 and 52, :being attached to the piston by the portion 52. The rod 45 extends beyond the cylinder 24 through the end cover 39. A wing nut 47 on the end portion 46 abuts a sleeve 48 surrounding the rod 45 and abutting the end plate 39. A spring 49 is positioned between the piston 40 and the end plate 39. The piston 40 has thereon a leather cup seal 41 held in position by a disc 42 and a nut 44 screwed onto the threaded portion 52. Movement of piston 4-0 by adjustment of the wing nut 47 effects Variation of the `volume of reservoir 24. Consequently, irrespective of the orientation of the hydraulic cutter or the quantity of liuidl in the reservoir 24, it is always possible to have uid available for delivery to the pump. Fluid can be supplied to the reservoir 24 through an opening 51 closed by a threaded plug 50. Also, a narrow through-bore 53 in the wall of the cylinder 1 allows, when uncovered, high-pressure fluid to escape from the cylinder 1, thereby limiting the travel or working stroke of the piston 2. It is arranged that the piston travel is limited so that the end of the working stroke occurs when the blade cutting edges 4a, 13a meet or almost meet.

In operation of the cutter, to cut say a chain link the screw pin 38 is released to open ball valve 37 and allow high pressure fluid to return to the reservoir 25 and thereby ensure that the piston 2 is brought to its innermost position by the spring 11. The disc 8 then abuts the face 23 of the block 22. Screw pin 38 is now screwed in to close the passage 36. The work piece in the form of a chain link is positioned on the base 21 and suitably orientated for cutting. The handle 28 is then operated to cause reciprocation of the plunger 27, so that fluid 25 is drawn from the reservoir 24 via passage 31 and delivered under pressure via passage 34 to the recess 35. Due to fluid pressure building up against the piston 2, the piston 2 and ram 3 are caused to move outwards, and the chain link is gripped between the cutting edges 4a -and 13a of the blades 4 and 13. With continued operation of the hydraulic pump and further increase of uid pressure in the cylinder 1, the resulting motion of the piston 2 and the ram 3 causes the blades 4 and 13 to penetrate opposite sides of the chain link. When the chain link is severed with the blades meeting or almost meeting, the piston 2 uncovers the relief bore 53. The high pressure fluid in the cylinder 1 then escapes, the motion of the piston 2 is arrested by the force of the spring 11, and cutting ceases; the screw pin 38 is immediately released to allow the fluid to flow back to the reservoir 25. The force of the spring 11 will now cause the piston 2 and the ram 3 to return to their innermost position where the disc 8 abuts the face 23 of the block 22. If during operation of the handle 28 it is felt that fluid is not passing from the reservoir 25 to the bore 26, the wing nut 47 is unscrewed. This causes the piston 40, under the action of the spring 49, to move towards the 'block 22 and force the fluid into the passage 31. The pump should then be able to operate satisfactorily. This diculty is most likely to occur when the hydraulic cutter is being operated vertically. When cutting is completed, the wing nut 47 is screwed down, thereby increasing the volume of the reservoir 25 to allow the high pressure fluid to pass back freely into the reservoir from the cylinder 1.

In a modification, the block 22 is screwed onto the cylinder 1 instead of being attached by welding, and similarly the cylinder 24 is screwed onto the block 22.

The hydraulic cutter is useful in cutting bars, joists, and other metal sections, and is especially suited for cutting in situ the metal joists which form the archways in coal pits.

I claim: 1. An hydraulic cutter comprising an hydraulic pistonand-cylinder actuating device; a U-support for the workpiece at one end of the cylinder of the actuating device; a cutting blade mounted on the piston of the actuating device and movable inwards from one limb of the U-support to penetrate the workpiece; a manually operable hydraulic pump at the other end of the cylinder of the actuating device and in fluid communication therewith; a cylindrical fluid reservoir in fluid communication with the pump and at the opposite side of the pump from and coaxial with the cylinder of the actuating device; and a spring-urged plunger in the reservoir for maintaining a uid supply to the pump irrespective of the orientation of the reservoir.

2. An hydraulic cutter as claimed in clairn 1, wherein the plunger includes a piston slidable in the reservoir and a piston rod extending slidingly through the outer end Of the reservoir, and adjustment means are provided on the rod end outwith the reservoir and are cooperable with the reservoir to cause adjusting movement of the piston and consequently variation of the effective volume of the reservoir.

3. An hydraulic cutter as claimed in claim 1, in which the actuating device includes a blade-carrying rod on the piston and slidable in the outer end of the cylinder, and `a key-and-groove connection between the rod and the outer end of the cylinder to retain the knife against rotation.

4. An hydraulic cutter as claimed in claim 1, wherein the U-support has a blade mounted on the other limb to co-operate with the blade on the first limb, and the blade on the outer limb is carried by a plug screwed into the outer limb, and cooperating formations on the plug and on a locking collar detachably secured to the outer limb prevent rotation of the blade.

References Cited UNITED STATES PATENTS 2,776,481 1/1957 Northcutt 30-180 3,093,024 6/1963 Pell 83-635 X 3,227,022 l/1966 Evans et al 83-698 X FOREIGN PATENTS 739,033 10/1955 Great Britain. 323,064 7/ 1902 France. 316,222 11/1956 Switzerland.

JAMES M. MEISTER, Primary Examiner. 

